Elucidation, cyclic voltammetry, computational studies, and biological activities of Ni(II), Cu(II), Cd(II), and Ce(III) complexes with a water‐soluble isonicotinohydrazide‐based Schiff base ligand

Abstract

Sodium salt of 4‐hydroxy‐3‐([2‐isonicotinoylhydrazineylidene]methyl)benzenesulfonate ligand (NaH2IH) was prepared, as an example of water‐soluble Schiff base ligands, by the condensation of isonicotinohydrazide with the sodium salt of 3‐formyl‐4‐ hydroxybenzenesulfonate. The chemical structure of the novel water‐soluble ligand and its complexes have been elucidated by analyzing the results of different spectroscopic and magnetic measurements. These structures were supported by the computational studies using density functional theory (DFT) technique. The ligand acts as mono‐negative bi‐dentate (ON) in [Cd(HIH)(H2O)Cl]2 complex, and as a tri‐negative tetra‐dentate (OONO) ligand in [Ce(IH)(H2O)2]2. In the [Cu(NaHIH)Cl]2.2H2O complex, NaH2IH behaves as mono‐negative tri‐dentate (ONN). Another mode of complexation displayed in [Ni(NaHIH)(H2O)Cl].2H2O dimer, whereas NaH2IH acts as a mono‐basic ON bi‐dentate. Based on the spectral data, one can assume a four‐coordinated tetrahedral geometry in case of all isolated complexes except Ce(III) one which has an octahedral geometry. The molecular structures and chemical geometries of the metal complexes were optimized and conformed using computational studies using DFT method. The outcomes of antioxidant activities reveal that the investigated compounds have good radical scavenging activity against ABTS and DPPH• radicals. The DNA binding ability of NaH2IH and its complexes has been examined by agarose gel electrophoresis methods. Wound healing was performed to test the antimetastatic activity of [Cd(HIH)(H2O)Cl]2 complex against MDA‐MB‐231 cancer cell line. Antimicrobial behavior of the compounds under study has been assessed against selected microorganism.